1. Field of the Invention
This invention is related to cable racks or trays and to walkways for accessing cable trays. In one particular embodiment, it is related to a cable tray walkway hinged at the side for movement away from the cable tray to permit access to cable tray and for emplacement over an adjacent cable tray.
2. Disclosure of Related Art
Conventional cable racks or trays are used in various industries to support a plurality of cables, pipes and other tubular members for transmitting fluid, gases, or electrical power to various locations, both indoors and outdoors, in a building, plant, refinery, or other facility. Generally cable trays are made from multiple interconnected tray sections which can be straight or curved to follow the contour of a wall or other structure. Individual tray components that are spliced together with conventional splicing structures can be easily disconnected, reconfigured, or re-positioned.
Two known types of cable trays each include a general channel construction with parallel side members or rails. In one type, perforated sheet metal forms the bottom of the cable tray. In another type, a plurality of transverse rungs or struts extend between the parallel rails to support cables, etc. These rungs can be mechanically or adhesively connected to the side members. Perforations in sheet metal or spaces between rungs provide for air circulation around the cables, permitting heat dissipation if desired.
The supported cables may be very small (e.g.,0.1 inches in diameter) or up to 5 or 6 inches in diameter or larger (usually limited by the depth of the tray, but cables could protrude above the top of the tray). Typically, a plurality of cables are disposed in each cable tray and a plurality of cable trays of the same or different widths may be positioned adjacent to one another. In typical operations, access to the cable trays is required for originally laying cable, for inspecting and repaining it, and for removing it. Prior unsafe practices include walking on the cables themselves or trying to balance on a tray side rail. Walking on the cables can damage them.
Walkways have been constructed next to cable trays. These structures can be relatively expensive and they can occupy space which might be used more beneficially. Also, such a structure adjacent a row of several cable trays does not provide access to the trays furthest away from the structure.
In accordance with 37 C.F.R. .sctn.1.56, the following are disclosed:
U.S. Pat. No. 4,733,986 discloses a splice plate for cable trays. PA1 U.S. Pat. No. 4,433,732 discloses a fireproofing system for cable trays in which the trays are enclosed in sheets of an intumescent fire retarding material. PA1 U.S. Pat. No. 4,244,545 discloses a clamp for a cable tray conduit. PA1 U.S. Pat. No. 4,046,343 discloses a cable tray with side plates, transverse supporting frames, and a cover plate secured to the side rails. PA1 U.S. Pat. No. 3,915,776 discloses a form for making reusable panels. PA1 U.S. Pat. No. 3,915,420 discloses a cable tray with side rails and transverse rungs. PA1 U.S. Pat. No. 3,851,378 discloses a method for making cable trays from side rails and transverse rungs. PA1 U.S. Pat. No. 3,770,233 discloses a cable tray draw mechanism for drawing cables onto trays. PA1 U.S. Pat. No. 3,618,882 discloses a cable tray with side rails and transverse cable supporting sections. PA1 U.S. Pat. No. 3,602,467 discloses a cable draw mechanism.
There has long been a need for safe and easy access to the cables, etc. supported in cable trays or racks. There has long been a need for such access to all of a plurality of adjacent cable trays. There has long been a need for a system for cable tray access which does not adversely impede the desired flow of air around cables in cable trays and in which the tray contents are adequately ventilated.